One of the problems faced by the perfumery industry lies in the relatively rapid loss of the olfactive benefit provided by odoriferous compounds due to their volatility, particularly that of “top-notes”. This problem is generally tackled using a delivery system, e.g. capsules containing a perfume, to release the fragrance in a controlled manner.
Polyurea capsules, formed by polymerisation between a polyisocyanate and a polyamine, are well known capsules that are used in a large variety of technical fields, including perfumery. Guanidine and guanidine salts are commonly used as polyamines in such capsules.
For example U.S. Pat. No. 5,635,211, US 2006/0216509, WO 2007/004166 and WO 2009/153695 all describe microcapsules having walls made of reaction products of guanidine or water-soluble guanidine salts and polyisocyanates or containing such reaction products.
Other polyamines are also used in polyurea microcapsules. For example, U.S. Pat. No. 5,225,118 discloses the use of ethylene diamine, hexamethylene diamine, diethylene triamine, triethylene tetraamine and tetraethylene pentaamine.
However, the olfactive performance of the prior art capsules still needs to be improved. Indeed the hedonic effect perceived by the consumer using a perfumed product, and therefore its perception of the quality of such a product, depends on the olfactive performance of the capsules. It is therefore desirable to provide capsules having a good olfactive performance in diverse products, including both home- and body-care products.
The present invention advantageously solves this problem by providing new polyurea microcapsules having improved olfactive performance in products such as detergents, hair care products and body lotions. Additionally the capsules of the invention have satisfying stability in consumer product bases and are even more stable than prior art capsules made with guanidine in some products, for example hair care products such as hair conditioners. To the best of our knowledge, the present solution to this problem is not described or even suggested in any prior art document.